Virgin Mobile USA announced today that it will offer the iPhone to its prepaid customers beginning June 29 for a pretty insane $30 a month unlimited data plan (throttled at 2.5GB) to celebrate the its 10th birthday this month.

Virgin Mobile will offer the iPhone 4 and iPhone 4S with its Beyond Talk unlimited data and messaging plans as low as $30(!)—opening up the iPhone to a whole new world of consumers. The Virgin plan requires registration for automatic monthly payments per-month on the Sprint Nationwide Network, but the plan is cancelable at any time. Purchase pricing on the iPhone is the same as Apple: iPhone 4S 16GB $649 and iPhone 4 8GB $549. That pricing suggests Cricket, a pre-paid carrier that announced the iPhone earlier for $399 for iPhone 4 and $499 for iPhone 4S with a $55 per month plan, is subsidizing the iPhone.

The iPhone will be available without a contract and with no fees for activation or roaming. New and existing customers can buy the iPhone at www.virginmobileusa.com, RadioShack, Best Buy, and select local retailers.

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“This month marks Virgin Mobile USA’s tenth birthday,” said Virgin Group founder Sir Richard Branson. “And what better way to thank our fans for ten years of loyalty than by giving them exactly what they want: the perfect plan for the perfect phone. That is the essence of ‘A Higher Calling.’”

Apple representative Natalie Harrison earlier said, “By making iPhone available on pre-paid plans [through Cricket Wireless], we are making the best smartphone more accessible to an even broader market in the US,”

Virgin Mobile’s Beyond Talk unlimited data and messaging plans for the iPhone start at $35 per month for access to Sprint’s Nationwide Network. Customers can also receive a $5 per-month plan discount when they register for automatic monthly payments with a credit card, debit card, or PayPal account, making the iPhone available for as low as $30 per month. Customers can even use their iPhone as a mobile hotspot through Virgin Mobile for an extra $15 per month. With purchase of Mobile Hotspot, plans include 3.5GB per month of full speed data.

For more information about iPhone on Virgin Mobile, including special alerts for when iPhone goes on sale on June 29, please visit www.virginmobileusa/iphone.